that can be fixed by changing what button changes the LEDs mode, open the Real_G27_ffb.ini and look at this
# mods available:
# 0 - LEDs off (for using with other LEDs plugins, fanaleds forr ex)
# 1 - time to next rest stop
# 2 - brakes temperature
# 3 - RPM
# 4 - fuel amount
# 5 - fuel average consumption
# 6 - time left for delivery in time
# 7 - cargo wear
mode=3
# button number to switch modes in cycle
leds_mode_switch_button_number=99 <------------ I changed it to 99 cause there is no button 99 on wheel so it never changes

check out this http://www.eurotrucksimulator2.com/multimon_config.php, it will show you the commands for messing with the monitors, If you get confused I suggest you go to SCS forums and post about it and Max, He is a DEV, will help you with it

try to right click while in the driving view, it should make the mouse look orange and then drag the box to move it. I run 3 screens too on r_multimon_mode = 2 and you cant move mouse from middle screen in menus cause of being in mode 2, it puts the menu on just the middle.